1. Field of the Invention
TURNING: Portable lathe; lathe with a tool and work rest; the work rest having a center rest. TURNING: Work driver.
2. Description of the Prior Art
U.S. Pat. No. 3,128,533 issued in 1962 to E. Haugland discloses a portable motor driven device for turning down and undercutting the commutators of motors and generators having shafts of different lengths and diameters. The drive means for turning the commutator is provided by an electric motor having an attached pulley. A pair of opposed bearings and brackets hold the ends of the commutator in position. An endless belt has one end looped and connected to the pulley on the drive motor while the other looped end surrounds and frictionally engages the armature. The rotating drive motor, pulley and endless belt cause the commutator to rotate so that one can true the commutator with an adjustable tool bit.
Radio controlled model cars have become a popular hobby, just as radio controlled model airplanes have been a popular hobby for decades. Radio controlled model cars and model airplanes are similar in that each has a self-contained motor and power source, each has a wireless receiving device in the unit, and each is controlled by a wireless transmitter that is operated by the hobbyist. Both hobbies are conducted out in the field or at large vacant parking lots. Field conditions require the hobbyist to take along with him or her a tool kit and spare parts because of frequent mechanical breakdown of the car or airplane.
The typical radio controlled car has four wheels attached to a frame. The frame holds the wireless receiver, control cables, a battery pack and the electric drive motor. The two rear wheels are the drive wheels, which are mounted on the frame and are interconnected by a drive shaft. The electric motor is mounted parallel to the drive shaft so that the rotating motor shaft rotates parallel to and in unison with the drive shaft. An endless belt interconnects a pulley on the drive shaft with a pulley on the electric motor shaft to transfer the power from the motor to the drive wheels. The typical electric motor used in radio controlled model cars runs on direct current usually at 7.2 volts or 8.4 volts. The motor has a compact cylindrical housing about two inches long and one and one-half inches in diameter. A cylindrical armature around a power shaft is rotatably positioned in the housing. A commutator is also secured adjacent to the armature. The commutator is cylindrical in shape, and it has a pair of brushes touching it through which electricity flows. The rotation of the electric motor is adjustable and is controlled by a speed control device mounted in the car. The speed control device is in turn controlled by the operator of the transmitter. The speed control device can adjust the amount of current flowing to the motor from the onboard batteries. The batteries used are nickel-cadmium rechargeable batteries so that the batteries can be recharged after each use. Each battery, which is called a cell, is usually 1.25 volts and is packed 6, 7, or 8 to a power pack for interchangeable replacement on the model car. The electric motor is capable of reaching 50,000 rpms at full power. The electric motor has very close tolerances. During model car races, the electric motor is operated at full power for extensive periods of time. The electric motor requires frequent cleaning and truing of its commutator, because of pitting, arcing, and normal wear and tear, to keep the motor operating at its full capability. Conditions encountered out in the field occasionally require the electric motor be removed from the car, disassembled, the commutator turned, and the motor reinstalled in the car.